InChI=1S/C18H15NO5/c20-13-7-5-12(6-8-13)3-1-2-4-17(22)19-16-10-9-14(21)11-15(16)18(23)24/h1-11,20-21H,(H,19,22)(H,23,24)/b3-1+,4-2+